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Your search keyword '"Sato, Fuminobu"' showing total 370 results
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370 results on '"Sato, Fuminobu"'

141. Improvement of microwave feeding on a large bore ECRIS with permanent magnets by using coaxial semi-dipole antenna.

Author

Kurisu, Yosuke, Sakamoto, Naoki, Kiriyama, Ryutaro, Takenaka, Tomoya, Nozaki, Dai, Yano, Keisuke, Sato, Fuminobu, Kato, Yushi, and Iida, Toshiyuki

Subjects
ELECTRON cyclotron resonance sources, ION sources, MICROWAVES, EXPERIMENTS, PERMANENT magnets, ION implantation
Abstract

We are constructing a tandem type electron cyclotron resonance (ECR) ion source (ECRIS). The first stage of this ECRIS has a large-bore with cylindrically comb-shaped permanent magnets. 2.45GHz and 11-13GHz microwaves can be supplied individually and simultaneously to the plasma chamber. For 2.45GHz, a coaxial semi-dipole antenna is used to feed the microwaves. In previous experiments, there were two problems encountered when running the 2.45GHz microwaves. High incident power was necessary to keep ECR discharge at low operating pressure because of high reflected microwave power. The surface of a support insulator between the inner and the outer electrodes of coaxial semi-dipole antenna was easily metalized by sputtering of the metal wall inside the chamber. The purpose of this study was to solve these problems. Performing several simulation experiments supports the hypothesis that the position of the support insulator is significant for microwave power efficiency. The end result was the ability to sustain ECR discharges at extremely low incident microwave power, several tens of watts, by optimized matching of the position and shape of the insulator. [ABSTRACT FROM AUTHOR]

Published
2012
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142. Enhanced production of ECR plasma by using pulse mode microwaves on a large bore ECRIS with permanent magnets.

Author

Kato, Yushi, Kiriyama, Ryutaro, Takenaka, Tomoya, Kurisu, Yosuke, Nozaki, Dai, Yano, Keisuke, Sato, Fuminobu, and Iida, Toshiyuki

Subjects
ELECTRON cyclotron resonance sources, PLASMA gases, MICROWAVES, PERMANENT magnets, ION bombardment, MAGNETIC fields, COMPARATIVE studies, ELECTRON temperature
Abstract

In order to enhance the efficiency of an electron cyclotron resonance (ECR) plasma for a broad and dense ion beam source at low pressure, the magnetic field configuration is constructed by all permanent magnets. By using the pulse mode, we aim at the generation of plasma with parameters that cannot be achieved in the CW mode at microwave frequencies of 11-13GHz, under the constraint of the same average incident microwave powers. It is found that the total beam currents are increased by the pulse mode operation compared with the case of the CW mode. According to probe measurements of the ECR plasma, it is found that the electron density in the pulse mode is larger than that in the CW mode, while the electron temperatures in the pulse mode are lower than that in the CW mode. These results are discussed from the viewpoint of relaxation times obtained on plasma parameters and ECR efficiency. The cause of the beam current increment and operational windows spread due to the pulse mode are also discussed on these parameters suitable to production of molecular/cluster ions. [ABSTRACT FROM AUTHOR]

Published
2012
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143. Ion beams extraction and measurements of plasma parameters on a multi-frequencies microwaves large bore ECRIS with permanent magnets.

Author

Nozaki, Dai, Kiriyama, Ryutaro, Takenaka, Tomoya, Kurisu, Yosuke, Yano, Keisuke, Sato, Fuminobu, Kato, Yushi, and Iida, Toshiyuki

Subjects
ION bombardment, MICROWAVES, PLASMA gases, PERMANENT magnets, ELECTRON cyclotron resonance sources, MAGNETIC fields, TRAVELING-wave tubes
Abstract

We have developed an all-permanent magnet large bore electron cyclotron resonance ion source (ECRIS) for broad ion beam processing. The cylindrically comb-shaped magnetic field configuration is adopted for efficient plasma production and good magnetic confinement. To compensate for disadvantages of fixed magnetic configuration, a traveling wave tube amplifier (TWTA) is used. In the comb-shaped ECRIS, it is difficult to achieve controlling ion beam profiles in the whole inside the chamber by using even single frequency-controllable TWTA (11-13GHz), because of large bore size with all-magnets. We have tried controlling profiles of plasma parameters and then those of extracted ion beams by launching two largely different frequencies simultaneously, i.e., multi-frequencies microwaves. Here we report ion beam profiles and corresponding plasma parameters under various experimental conditions, dependence of ion beams against extraction voltages, and influence of different electrode positions on the electron density profile. [ABSTRACT FROM AUTHOR]

Published
2012
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147. Multi-Frequency Microwaves Plasma Production for Active Profile Control of Ion Beams on a Large Bore ECR Ion Source with Permanent Magnets.

Author

Sakamoto, Naoki, Kato, Yushi, Kiriyama, Ryutaro, Takenaka, Tomoya, Sato, Fuminobu, and Iida, Toshiyuki

Subjects
MICROWAVE plasmas, ION bombardment, ELECTRON cyclotron resonance sources, PLASMA gases, PERMANENT magnets, ION sources
Abstract

A new concept on magnetic field of plasma production and confinement by using permanent magnets, i.e. cylindrically comb-shaped magnets, has been proposed to enhance efficiency of an electron cyclotron resonance (ECR) plasma for broad and dense ion beam source under the low pressure and also the low microwave power. The resonance zones corresponding to the fundamental ECR for 2.45 GHz and 11-13 GHz frequency are constructed at different positions. The profiles of the plasma parameters in the ECR ion source are different from each frequency of microwave. Large bore extractor is set at the opposite side against the microwave feeds. It is found that differences of their profiles also appear at those of ion beam profiles. We conducted to launch simultaneously multiplex frequency microwaves controlled individually, and tried to control the profiles of the plasma parameters and then those of extracted ion beam. [ABSTRACT FROM AUTHOR]

Published
2011
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